when is your ovulation Is it the green day?

Hi everyone my hubby and I are trying for our 1st baby together he's got two boys and I've got 4 boys needless to say we are really hoping for a girl this time. I have been reading a lot about stopping intercourse 3 days before you ovulate to allow the girl sperm to get to the egg before the boy sperm. I have tested my pH and I have a very alkaline body which is a good environment for the boys sperms but I'm confused about the window the fertility window is the ovulation day the last day that's marked green or is it earlier where it says you have a higher chance of getting pregnant. Thank you in advance for any advice in understanding this.